Devices are known for protecting threaded connections of pipes. As used herein the term “pipe” should be construed broadly to encompass any tubular members, including, but not limited to, pipes, tubes, connectors, conduits, fittings, and the like.
One technique that has been used to protect threaded connections of pipes from dust and corrosive fluids is to wrap the pipe ends with plastic film.
Various other thread protectors have also been developed. These conventional protectors typically employ a plastic protector to prevent mechanical damage of the threaded areas, while corrosion is prevented by applying a storage compound or grease. Several different approaches have been used for dealing with corrosion. For example, U.S. Pat. No. 5,352,383 discloses using a liquid corrosion inhibitor applied to the pipes. U.S. Pat. No. 5,452,749 discloses using an external sealing device to keep out contaminants, but it does not includes an internal sealing device.
U.S. Pat. Nos. 4,582,090 and 4,796,668 disclose thread protectors using internal and external sealing devices. The internal and external sealing devices disclosed in both of these patents are formed integrally with the body of the thread protector. Accordingly, the sealing devices are made of the same material as the body of the thread protector. With this arrangement, the material of the sealing members is limited by the strength requirements of the body of the thread protector. The relatively stiff materials required to provide rigidity to the body of the thread protector disclosed in the '668 patent cannot adequately seal against the pipes. Adequate flexibility of the sealing members is required to ensure proper sealing. The '090 patent attempts to remedy this problem by providing a metallic shell outside the body of the protector to provide rigidity to the thread protector. The additional shell of the thread protector disclosed in the '090 patent increases the cost and complexity of the thread protector. Also, since the body of the thread protector of the '090 patent is made of the same relatively soft material as the seal members, the threaded interface between the protector and the pipe cannot be made as strong as if the body were made of a harder material.